Member

Pressures washer are messy blasting the moss everywhere, and it there is any problems with the roof - cracked, weakened or loose tles, then the PW can damage them and blast in water below them. And if you did by chance accidentally hit the tiles with a PW from below, or from the side on some tiles, you most certainly will blast water in below the tiles and cause damp for your customer.

In my opinion, the best way is to get up there with a stiff brush and brush it off. You may also want a painters scraper to get in the little awkaward bits.

If it a flat slate roof, you may be able to do it from the gutter level with a stigg brush on the end of an extension pole. But any other slates, you will probably need a roof ladder and get up there, brushing the moss down from the top.

If you want the moss to stay away for a while afterwads, you will need to treat with biocide after the moss has been removed.

Member

WWC makes a very good point!! My main job is roofing with my dad and we see so many cowboys up on roofs blasting their pressure washers left, right and center. This causes so many problems as many of the roofs with moss on are likely quite old and could do without all that strain. We don't mind as it brings us more work but yeah would never recommend it as it's terrible for the roof, get up there with a trowel and a stiff brush, start on the top course of tiles and work your way along